Process of chlorination of methane



Patented Aug. 6, 1 929.

UNITED STATES PATENT ornca,

KOLOMAN ROKA, OF CON STANCE, GERMANY, ASSIGNOR TO THE EIBM OI HOLZVER- I KOHLUNGS- INDUSTRIE .AKTIEN-GESELLSOHAFT, OI" CONSTANCE (BADEN), GER- MANY, A CORPORATION OF GERMANY.

PROCESS OF CHLORINATION OI MET HANE.

m'nmwm Application filed October 14, 1921, Serial m. 507.755, and in' Germany mm 18, 1920.

The known processes for chlorinatingmethene can be divided into two groups, viz:

3a) those which work at low temperature an in which the energy required for the in- 5 itiation and for the maintenance of the reaction has the form of light or the form of electric energy (silent electric discharges),

(5) those which are carried out at high temperature, in which the energy is supplied in the form of heat.

With both-working methods it is necessary to moderate the reaction which takes place under strong development of heat, eventually under explosion by the addition of a vdiluent.

As such diluent, nitrogen or carbon dioxide has been proposed mainly or one of the components of reaction itself. Steam has been proposed also as'a diluent but only for the light methods carried out at ver low temperature for instance 80-100 C. see Chemisches Zentralblatt 1913,11, page 99) whichpermit the unobjectionable application of this diluent.

For the heat methods which are carried.

out at high temperatures, for instance 400500 0., the use of steam as diluting agent seemed however to be excluded from the beginning as it is known that at these temperatures chlorine and steam act on each other very rapidly with the formation of oxygen. Applicant has now made the surprising observation that the harmful reactions do not occur. As. has been found out, the chlorine seems to possess a selective afiinit'y so that it does not attract the hydrogen of the steam but the hydrogen of the methane. The undesired reaction 2Cl 21-1 0 4HC1+ O consequently does not take place but surprisingly the process goes on smoothly in the desired direction for instance CH,+ GI,=GH,C1+HC1.

The steam does therefore unexpectedly not participate in the reaction, despite thev which are to be obtained.

cessful and to avoid undesired secondary reactions it 1s necessary to watch the temperav ture because at excessively high temperatures the undesired decomposition of water will take place and carbonic acid and carbonic oxide are obtained in the exit gases. The percentage of steam can vary within considerable limits. Generally the use of 2 to 3 volumes of steam for one volume of chlorine has proved to be suflicient..- In certain cases even an ad-.

apparatus, the maximum temperature, the

correct guantity 'of steam and the maximum speed 0 by simple gas analysis (determination of carbonic dioxide and carbonic oxide).

. The use of steam offers in comparison with the use of gases such as nitrogen and carbonic acid the advantage, that no foreign gases are introduced into the product of reaction. Over the use of these gases or of methane in excess there is further realized a progress in so far as a much smaller excess of steam is required to absorb the liberated heat and to remove the same. Another essential advantage consists in this that the isolation of the the gases can be easily ascertained product of chlorination, e. of the methyl detrimental, the greater the quantity of the diluting agent em loyed, e. g. methane. As nowextraordinari y reatquantities of methane in excess are requlred just for the roduction of a rincipal product of chlorination, methyl ch oride, the advantage of the-utilization of steam is'quite obvious. A further ad.-

vantage over the process which works with methaneexcess consists in the possibility of regulating accordin to the improved process the proportion of c lorine and methane. in accordance with the products of chlorination Other diluting means, for instance methane, can however be used besides the steam, in Which case the advantage is obtained that 'much smaller quantities of these auxiliary diluting means are required than hitherto.-

'The process can be carried through'as well in the presence and in the absence of catalyzing agents, such as cupr'ic chloride, ferric chloride and others. The halides of the alkaline earths, for instance-chloride of calcium, chloride of magnesium and others have been shown to be Very eficient catalyzing substances; they could be used eventually with convenient diluting means for instance upon porous carriers. I V

It has been found out further that the steam can be utilized simultaneously'to introduce into the reaction space the heat required for the reaction from which results the adantag'e thatno heating from the outside is necessary, thereby simplifying the plant.

I claim 2'"- 1'. In the heat method of chlorinating meth ane, the steps which. comprise chlorinating methane in the presence of steam as a diluent at a temperature of 400'-500 (l, andkeeping the temperature below that at which subcatalyst is a halide of an alkaline earth metal.

4. The process as in claim 2 in which the a catalyst is.calcium chloride.

In testimony whereof I have si ned my name to this specification.

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